1. Field of the Invention
The present invention relates to a magnetoresistance effect element or magnetoresistive element for reading magnetic field intensity as signals in a magnetically recorded medium and a method of fabricating the same, and in more particular to a magnetoresistance effect element which is fabricated with a magnetoresistive film having high rate of change in resistance in a small external magnetic field and a method of fabricating the same.
2. Disclosure of the Related Art
In these years, in association with an advance in a high sensitivity in magnetic field sensors and a high density in magnetic recordings, the development of magnetic field sensors of magnetoresistance effect type (hereinafter referred to as "MR sensor") and magnetic heads of magnetoresistance effect type (hereinafter referred to as "MR head") arises increasingly. The MR sensor and MR head read external magnetic signals through the resistance change in a reading sensor part comprising a magnetic material. However, in the MR sensor and MR head, the relative speed thereof with respect to a magnetic recording medium does not depend on a regenerative or reproducing output and thus the MR sensor achieves a high sensitivity and the MR head attains a high output even in case of a high density magnetic recording.
Recently, a magnetoresistance effect element comprising two or more of magnetic thin layers which are stacked with intervening a non-magnetic thin layer therebetween, wherein adjacent magnetic thin layers through the non-magnetic thin layer have different coercive forces and the element exhibits a large magnetoresistance change in a small external magnetic field, has been taught in Unexamined Japanese Patent Publication Hei 4-218982 (EP 0 483 373 A1). This magnetorsistance effect element has a high resistance change rate of several % to several tens % in a small external magnetic field of the order of several Oe to several tens Oe.
The magnetoresistance effect element as described in the above publication can be operated by application of the small external magnetic field. However, if the element is used for practical sensors and magnetic heads, it was necessary to set bias layers on the upper and lower sides of the element or to apply an external bias magnetic field thereto.